Case Report pISSN 1738-2637 / eISSN 2288-2928 J Korean Soc Radiol 2018;79(1):40-44 https://doi.org/10.3348/jksr.2018.79.1.40

Mucinous Adenocarcinoma Arising within a Colonic Mimicking a Diverticular : A Case Report 게실 농양으로 오인할 수 있는 결장 게실에서 기인한 점액선암종: 증례 보고

Goun Choi, MD1, Jiyoung Hwang, MD1*, Seong Sook Hong, MD1, Jae Joon Kim, MD2, In Ho Choi, MD3 Departments of 1Radiology, 2Surgery, 3Pathology, Soonchunhyang University College of Medicine, Seoul Hospital, Seoul, Korea

Colon cancer arising in a colonic diverticulum is very rare. There are only a few re- ported cases of colon cancer associated with a diverticulum. Of these reported cases, Received December 26, 2017 only a few are those of a mucinous adenocarcinoma. Here, we report a case of an Revised February 13, 2018 Accepted March 20, 2018 82-year-old female with a mucinous adenocarcinoma arising in the ascending co- *Corresponding author: Jiyoung Hwang, MD lonic diverticulum, which clinically and radiologically mimicked perforated divertic- Department of , Soonchunhyang University College of Medicine, Seoul Hospital, 59 Daesagwan-ro, ulitis with abscess formation. Although such cases are rare, our findings suggest Yongsan-gu, Seoul 04401, Korea. that malignant tumors may be misdiagnosed as diverticular diseases and should be Tel. 82-2-709-9396 Fax. 82-2-709-3928 considered during work-up. E-mail: [email protected] This is an Open Access article distributed under the terms Index terms of the Creative Commons Attribution Non-Commercial Diverticulum, Colon License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distri- Colonic Neoplasms bution, and reproduction in any medium, provided the Adenocarcinoma, Mucinous original work is properly cited. Abscess

INTRODUCTION er quadrant. Her pain started one day before, was persistent, and rated as moderate (Numeric Rating Scale 6). She did not Diverticular disease is a common colonic disease. Diverticu- have other gastrointestinal symptoms such as vomiting or diar- litis occurs in about 10–25% of patients with and rhea. Physical examination on admission showed tenderness is sometimes combined with perforation, abscess, or for- and rebound tenderness at the right lower quadrant and a mation (1). Although rare, colon cancer can develop from the of 38.3°C. On laboratory examination, her white blood cell mucosa of a colonic diverticulum. This rarity, together with count was 18700/µL (normal, 4000–10000/µL) with neutrophil- sometimes non-specific imaging findings, complicates differen- ia of 78.12%. The C-reactive protein was elevated to 5.75 mg/dL tial diagnosis from common diverticular disease. In this report, (normal, 0.0–0.5 mg/dL). The patient had no specific medical we describe a rare case of mucinous adenocarcinoma arising in history except for hypertension and hyperlipidemia. She denied a colonic diverticulum without diverticulitis or abscess forma- a previous history of colonic diverticulitis. Contrast-en- tion, mimicking a perforated diverticular abscess. hanced abdominal computed tomography (CT) revealed a 4.8 × 3.9 × 3.8 cm peripheral-enhancing, low-attenuated, exophytic Case Report mass like lesion at the medial wall of the proximal ascending colon. The lesion connected to the lumen of the proximal as- An 82-year-old female was admitted to our emergency de- cending colon via an out-pouching sac, indicating a colonic di- partment with acute localized to the right low- verticulum. The outer margin of the diverticulum was not de-

40 Copyrights © 2018 The Korean Society of Radiology Goun Choi, et al fined, but contained a small amount of air (Fig. 1A, B). There traperitoneal free air was seen. The and other pelvic was no calcification within the mass like lesion. Mild soft tissue organs were unremarkable. Based on abdominal CT findings of stranding was noted in surrounding fat. An involved segment an out-pouching diverticulum, low-attenuated mass like lesion of colon showed mural thickening with preservation of the lay- surrounding a diverticulum, and mural thickening of involved ering pattern. There were multiple enlarged lymph nodes at the colonic segment with preservation of the mural layer and clini- right lower quadrant, the largest of which was 9 × 17 mm in di- cal and laboratory features of acute abdominal pain, fever, and ameter. Lymph nodes were round or oval with regular borders leukocytosis, the was perforated colonic and homogeneous enhancement (mean, 45 HU on pre-contrast diverticulitis with abscess formation. However, the possibility images; mean, 150 HU on contrast-enhanced images). No in- of colon cancer was also considered because of the exophytic

A B

C D Fig. 1. A 82-year-old female with a mucinous adenocarcinoma arising in ascending colonic diverticulum. A. Axial contrast-enhanced abdominal CT showing a peripheral-enhancing, low-attenuated, exophytic mass at the medial wall of the proximal ascending colon. The mass is connected to the lumen of the proximal ascending colon via an out-pouching sac (arrowhead), indicating a colonic diverticulum. Mild soft tissue stranding was noted in the surrounding fat. B. In the coronal reformatted image, the involved segment of the colon shows mural thickening with preservation of the layering pattern (ar- rows). The appendix is unremarkable. C. The opened lumen of the colon specimen showing a large diverticular opening (arrow) with intact overlying mucosa. D. Cut section revealed an irregular mass in pericolic soft tissue, involving the colonic wall (6.0 × 5.5 cm). jksronline.org 대한영상의학회지 2018;79(1):40-44 41 Mucinous Adenocarcinoma Arising within a Colonic Diverticulum

E F Fig. 1. A 82-year-old female with a mucinous adenocarcinoma arising in ascending colonic diverticulum. E. The mucosa lining the diverticulum is eroded (arrow) along the diverticular opening (asterisk). An abundant mucin pool with tumor cell nests was present in the deeper portion of the diverticulum (hematoxylin and eosin stain, × 12.5). F. The mass has floating, single, or nested tumor cells in the mucin pool (hematoxylin and eosin stain, × 100). mass, which showed a relatively mild degree of soft tissue ated with colonic diverticular abscess was first described by stranding in peri-lesional fat. The patient underwent ileocecec- Tolley in 1967 (2), only a few cases of colon cancer associated tomy with lymph node dissection. Intraoperatively, an 8 cm with a diverticulum have been reported (3-5). Several investiga- mass was identified at the ascending colon without abscess for- tors have tried to show an increased incidence of colonic carci- mation. noma in patients with diverticulitis, suggesting that chronic in- Macroscopically, there was a large diverticular opening at the flammation leads to metaplasia and neoplastic changes (4, 6). proximal ascending colon, but the surrounding mucosa was However, other investigators have argued that there is no spe- otherwise grossly unremarkable (Fig. 1C). Cut sections revealed cific relationship between diverticulitis and carcinoma based on an irregular mass in the pericolic soft tissue, involving the co- the following evidence: 1) the rarity of adenocarcinomas arising lonic wall (Fig. 1D). Microscopically, the diverticular opening within diverticular mucosa, 2) the absence of occasional dys- was lined by mucosa invaginating into the muscularis propria. plasia in diverticular mucosa, and 3) the often documented oc- Tumor cell nests with an abundant mucin pool occupied the currence of adenocarcinomas in areas with no diverticula (7). diverticular space and extended through the diverticular wall In our case, histopathological examination of the colonic speci- to the pericolic soft tissue with involvement of a pericolic men showed carcinoma within a diverticulum without involve- lymph node (Fig. 1E, F). Immunohistochemical findings sug- ment of the colonic mucosa. There was no histopathological gested a neoplasm of intestinal origin rather than a metastatic evidence of chronic or abscess. malignancy (CDX-2+, CK7-, CK20-, GCDFP-15-, TTF-1-, Mucinous adenocarcinoma is a histopathological subtype of PAX-8-, ER-). Based on the pathologic findings, a moderately characterized by abundant extracellular mu- differentiated mucinous adenocarcinoma arising in a colonic cin pools (8). In previous studies that compared imaging find- diverticulum was confirmed. After surgery, the patient received ings of mucinous colorectal carcinoma with non-mucinous adjuvant chemotherapy. carcinoma, mucinous carcinomas frequently showed bowel wall thickening greater than 2 cm, eccentric bowel wall thick- Discussion ening, heterogeneous contrast enhancement of the tumor, poor contrast enhancement of the solid tumor component, a large Colonic diverticular disease is common, but colon cancer aris- area of low attenuation within the tumor, and intratumoral cal- ing in a colonic diverticulum is rare. Since colon cancer associ- cification on contrast-enhanced CT. They also showed high sig-

42 대한영상의학회지 2018;79(1):40-44 jksronline.org Goun Choi, et al nal intensity on T2-weighted images, with a peripheral contrast References enhancement pattern on MRI, in contrast to non-mucinous carcinomas (7, 9). Consistent with previous findings, the mass 1. Jacobs DO. Clinical practice. diverticulitis. N Engl J Med in our case showed low attenuation with poor contrast en- 2007;357:2057-2066 hancement on CT. The mass had no intratumoral calcification. 2. Tolley JA 3rd. Chronic diverticulitis with perforation and as- These findings mimic an abscess cavity, complicating the diag- sociated carcinoma of the cecum. Dis Colon 1967; nosis. However, we considered the possibility of colon cancer 10:389-393 due to the weak soft tissue stranding in peri-lesional fat. 3. Kwon JH, Han KH, Chang WS, Nam KH, Han MS, Ahn JH, et Two cases of a mucinous adenocarcinoma developing in a al. A case of a mucinous adenocarcinoma arising from a diverticulum have been reported (3, 5). Kwon et al. (3) reported rectal diverticulum. J Korean Soc Coloproctol 2012;28:222- a rare case of mucinous adenocarcinoma arising from a rectal 224 diverticulum. In that case, radiologic and endoscopic findings 4. Kikuchi T, Kotanagi H, Kon H, Koyama K, Ito S, Otaka M. Mu- suggested primary rectal cancer, and the rectal diverticulum cosal carcinoma within a colonic diverticulum. J Gastroen- was not visible on radiologic and endoscopic examination. In terol 1999;34:622-625 the second case (5), a mucinous adenocarcinoma was inciden- 5. Soliman ML, Cerda SR, Xu H. Invasive moderately-differen- tally identified in perforated colonic diverticulitis with abscess tiated mucinous adenocarcinoma incidentally identified in formation. To the best of our knowledge, the present case is the perforated acute diverticulitis with abscess formation. first report of a mucinous adenocarcinoma arising in a colonic Pathol Lab Med Open J 2016;1:32-36 diverticulum without diverticulitis or abscess formation. Due 6. Mayo WJ. Diverticulitis of the . JAMA 1917: to the rarity of carcinoma development within a diverticulum, 781-785 it is easily missed. Furthermore, difficulties in differentiating 7. Rowe RJ, Kollmar GH. Diverticulitis of the colon complicat- between colon cancer and diverticulitis with or without abscess ed by carcinoma. Int Abstr Surg 1952;94:1-9 formation are well recognized (10). Meanwhile, malignant tu- 8. Park JS, Huh JW, Park YA, Cho YB, Yun SH, Kim HC, et al. mors arising within a diverticulum can easily penetrate the se- Prognostic comparison between mucinous and nonmuci- rosa due to lack of a muscular layer (4). In our case, the tumor nous adenocarcinoma in colorectal cancer. Medicine (Bal- penetrated through the diverticular wall into pericolic soft tis- timore) 2015;94:e658 sue and a pericolic lymph node. It is important to consider the 9. Hussain SM, Outwater EK, Siegelman ES. Mucinous versus possibility of malignancy when diagnosing diverticular disease, nonmucinous rectal carcinomas: differentiation with MR especially when unusual imaging features are observed. imaging. Radiology 1999;213:79-85 In summary, we describe a rare case of mucinous adenocar- 10. Chintapalli KN, Chopra S, Ghiatas AA, Esola CC, Fields SF, cinoma arising in the colonic diverticulum, mimicking a perfo- Dodd GD 3rd. Diveriticulitis versus colon cancer: differenti- rated diverticular abscess. Despite its rarity, the possibility of a ation with helical CT findings. Radiology 1999;210:429-435 malignant tumor masquerading as diverticular disease should be considered to improve patient management and prognosis.

jksronline.org 대한영상의학회지 2018;79(1):40-44 43 Mucinous Adenocarcinoma Arising within a Colonic Diverticulum

게실 농양으로 오인할 수 있는 결장 게실에서 기인한 점액선암종: 증례 보고

최고운1 · 황지영1* · 홍성숙1 · 김재준2 · 최인호3

결장 게실에서 기인하는 대장암은 매우 드물다. 게실과 연관된 대장암의 보고된 사례는 소수에 불과하다. 이 보고된 사례 중 소수만이 점액선암종이었다. 저자들은 상행 결장 게실에서 점액선암종이 발생한 82세 여자 환자에서 임상적 및 영상의 학적으로 농양을 형성한 천공성 게실염으로 오인된 증례를 경험하였기에 보고하는 바이다. 이 증례는 비록 드물지만, 악성 종양을 게실 질환으로 오인할 수 있으므로 진단 중에 주의를 기울여야 함을 시사한다.

순천향대학교 의과대학 서울병원 1영상의학과, 2외과, 3병리과

44 대한영상의학회지 2018;79(1):40-44 jksronline.org